Seca650 No spark

it is a rubber jacket connector cover a little wd or silicon under end it should pull apart
black/white wire runs from tci connector. bullet con is about 5 inches down the wire

you have to remove tank to find the sidestand relay

 

Ok, I was able to disconnect the b/w wire from the TCI and unfortunately it didn't change the situation. I'm still able to turn the engine over but not getting a spark of any kind. Any other ideas? Everything checks out to spec as far as the coils, ignition and pick up. Fuse box looks good and I cleaned the connections with sand paper to get them bright and shiny. Battery is also good as it's the one that I use for my other bike and it's only 6 months old.

 

Is this the correct side stand switch, btw? Would this be the female connection that would fit directly into male connection that the PO jumped as indicated in the picture I posted earlier?
https://www.ebay.ie/itm/1982-YAMAHA...742749?hash=item4d72dfab1d:g:wV8AAOSwLEtYj2Jo

 

That's the right one.

 

1. Just to be sure you are checking for spark correctly check one cylinder at a time with the other 3 plug wires connected to the spark plugs with the plugs installed. Using a spare new plug for the cylinder under check is advisable but a known good used plug would be OK. It is important that the other plugs are connected with the wasted spark system to have a complete current path to produce a spark. Connect the spark plug to the cylinder under test plug wire and ground the threads to the aluminum head. Crank the motor and look for spark - note XJ bikes produce a weak spark so in the garage or shade is advised.

2. Since there is evidence of the PO being creative check the voltage at the TCI just to be sure 12V is present with the key on and the kill switch set to RUN. On the 4 pin connector at the TCI there should be 12V on the R/W wire in respect to ground. So connect the black lead of the DMM to chassis ground or battery negative and with the red lead back probe the R/W wire at the TCI to verify 12V. Note that the voltage should remain above 9.5 (See edit below) volts during cranking also as the TCI becomes active and draws considerably more current. Next move the red lead to the black wire on the 4 pin connector and verify 0V to verify the TCI is properly grounded.

3. If the voltage checks out OK to the TCI, and since you have verified the external pick-ups and coil resistance, as well as disabling the ignition cutoff by disconnecting the B/W wire, then the TCI could be faulty causing no spark.

4. There are a couple of checks that can be done to check the TCI with just a DMM, but an oscilloscope is really required to test it. Or, the other option is have another member try it on their bike - anyways you can do this also.

a. Place the DMM on the gray wire on the TCI 4 pin connector and the DMM black wire to battery negative. Turn the key switch on and observe the DMM - it should show a low voltage (approx 1.4 VDC) for just a couple of seconds and then change to 12V. If this is occurring, you should also see one spark occur on the 2, 3 plugs as the voltage changes from 1.4VDC to 12VDC. Note this is dependent on the position of the reluctor in relation to the pick-up coils, so if the gray wire does not go low momentarily, try the orange wire.

b. Remove the left side crank cover and turn the crankshaft CCW to center the reluctor between the pick-up coils. Place an external plug in the number one spark plug cap and the number two spark plug cap and ground the threads of the plugs to the aluminum head. Turn the key on and wait a few seconds - one of the two plugs should produce a spark but this can be a bit ambiguous as it does not always occur. After waiting, place a thicker feeler gauge against the number 1,4 pick-up (you should feel the magnet) and then flick the blade sideways. Once again this is a bit ambiguous on which plug will spark because of the internal design of the TCI, but either the 1 or 2 plug should spark after a second or two. Repeat on the 2,3 pick-up (top with gray wire).

Edit: The voltage at the R/W wire during cranking when the TCI becomes active is likely to be in the 8 to 9VDC range. Ideally, it should be higher but losses in the main fuse, ignition fuse, kill switch, and wiring will result in a value lower than the battery load test. Verifying the condition of the fuse box, ignition switch, and kill switch would be advisable for lower voltages.

 

Wow. Quite a list of things to try. I'll get cracking. Thank you.

Btw, for the hell of it I opened the stator cover and measured the copper rings. It came out to 4.1 ohms. Brushes look excellent.

 

In the meantime, are there any Seca or Maxim 650 or 750 owners in LA?

 

Just curious, I have access to a TCI from both an xj550 and an xj750. I know these are not the correct TCI"s but would it at the very least fire the bike up thus showing that my TCI is bad?

 

seca 650 has a non yics motor so that's what you need a tci from,
if the wiring is the same at connectors it will fire the bike but will not run well.

 

Rooster, I have some very telling news. I conducted the test where I attached the red probe to the R/W wire on the 4 pin connector to the TCI and when I turned the switch on I only read 9.98volts (battery measured 12.88 before testing) When I turned the engine over it went all the way down to 8.0volts. However, when I moved the red probe to the black wire it was indeed grounding to zero. What do I do next?

Also, as an experiment I tried my TCI from an xj550 and that didn't change anything.

 

The battery is a goner. Replace with new.

 

Since I've been using the battery from my other bike and I just installed a new one I received in the mail I highly doubt a bad battery is my problem. I also did a load test at the battery terminals and it only goes down to 10.63 volts.

I can't tell but is it worth changing the fuse box? It looks really good and clean but it's the original glass fuse box, however, I measured zero resistance when I checked each fuse terminal.

I also read in another post that a gentleman had a lot of resistance between the R/W and B wire at the TCI unit which disappeared when he replaced it. However, he had 75 ohms and when I checked my resistance it came out to 6.1. It's not as much but I understand it should be zero.

 

have you replaced the out of spec spark plug caps yet?

disconnect the head light or pull the head light fuse to lessen voltage drop

if you wish to stand by the battery you have then it is time to start cleaning connections.
start be cleaning ignition switch.and battery cables. clean the connector that goes from positive battery terminal to main fuse.

a new inline fuse holder for the ignition fuse. clean the run/kill switch and associated connections. tci connections and ignition coil connections.
clean connections on solenoid and at starter.
use electronic spray cleaner and a dab of dielectric grease to prevent future corroision.
Every connector can cause voltage drop do a voltage drop test at tci when cranking after cleaning

if you have 9.98 volts at tci you are at the no start threshold.
if you have access to a car battery that would help with the voltage drop.

your starter could be drawing to much power, causing the voltage drop. it may need to be rebuilt or replaced.

new batteries can be crap from the package. I just got a new battery it was defective . it does happen

I do not want to lead you down the road of parts replacement if they are not needed.

a spare tci is always a good thing but that's money you could have spent on a fuse box or starter rebuild kit.

 

Well, I believe those numbers are OK and your battery is fine. I will edit that number of 9.5VDC at the R/W wire when cranking as that number does not account for the losses that occur in the fuses, ignition switch, kill switch and wiring. For what it's worth, I just checked my 750 Seca which has been sitting a while and the battery is a bit depleted and about 5 years old. Numbers were:

Battery 12.1 volts, cranking dropped to 9.8 volts
R/W wire key on 9.7 volts and then rising to 11.1 volts when the TCI switched to standby mode after approximately 2 seconds - 7.4 volts when cranking.

Note with these voltages it has no problem producing a spark and starts easily.

So, not sure where to say to go next since now you have tried another TCI and verified coil and pickup resistance. Note from the earlier post you do need to replace the 1 and 4 spark plug caps as they are out of spec, but I still believe they are not so far out as to prevent a visible spark. Just to be sure though it would be advisable to check spark on 2, 3 cylinders since those reading are well within spec.

Guess I might ask did you notice a lower static voltage on the TCI R/W wire when the key switch is first turned on and then changes to a slightly higher voltage after about 2 seconds? This is important as it indicates the TCI is going active and one of the output transistors has switched on sinking current through one of the ignition coil primaries. That change in voltage at the R/W wire should also be noted if you do the test with the feeler gauge as it will produce a pules activating the TCI for a couple of seconds much like the power up situation.

That really shouldn't read zero. When you measure between the R/W wire and black wire at the TCI the displayed resistance is the value of the neutral bulb and associated wiring, fuses, and switches. If you switch the bike out of neutral it will go considerably higher. Note also at least on my 750 the neutral switch tends to have a bit of resistance, which makes testing the wires this way a bit ambiguous. A point to point test would be more appropriate - R/W wire to battery positive cable (battery disconnected) with the key and kill switch set to run would show the total resistance of the wire, kill switch, ignition fuse, ignition switch, and main fuse.

.

 

make sure you clean the case and frame ground terminals before going into more voltage drop testing.

 

Rooster, I DID NOT notice a change in voltage at the R/W wire after turning the key on. It stayed at around 9.8 volts the entire time.

Also keep in mind that the TCI unit I used as a substitute was from an xj550 and I noticed the wire arrangement on there is different then the 650. From what I researched the 1982 xj650rj Seca has a TCI unit that's all it's own and cannot be interchanged.

I also checked the voltage at the fuse box when turning the key on. The Main fuse displayed around 12.2volts while the other three would read around 11.23volts. I read that they should all be at least 12 but I'm not sure.

Also remember the side stand switch is completely gone but I think I would not even be able to crank over if that was the issue. Yes?

I'm assuming it would be in my best interest to track down a TCI before completely ruling that out?

 

you will need the correct tci for that motor.


if sidestand were working correctly the motor will not turn over when starter button pushed with the motor in gear and stand down.
your side stand switch bypass does not look as if it a problem.
have you tried swapping the sparkplugs into the other cylinders to see if the problem follows the spark plugs or put in new sparkplugs to eliminate them as the problem?


so if you have your ignition system in spec and are happy with your battery condition then it is time to get another TCI.

 

The spark plugs are brand new. The PO replaced them when he tried to fix the bike. I've tried one at a time looking for spark in all the plugs and was unsuccessful.
The hunt for a TCI is on.

 

With a good battery (which you seem to have) the 9.8 volts is similar to the voltage that is present at power up when the TCI pulls one of the coils low. If it is staying at 9.8 volts that may indicate a constant on condition for one of the TCI channels. You can easily check that by measuring the voltage on the Orange and Gray wires (coil primaries) on the 4 pin connector. With the key on they both should be close to 12 volts after a couple of seconds as the TCI switches to standby mode - normally one or the other will go low for a couple of seconds when the TCI is powered on.

((Edit: This is not true - the pinout is different for the 4 pin connector.))
((Edit the Edit - turns out the below is true, and the Haynes / Yamaha diagrams are incorrect))
From what I can tell from some of the wiring diagrams that I have they should be the same pinout, and the XJ550 TCI should produce a spark. @XJ550H perhaps he could verify as he has both models. We need to be sure the PO did not do something creative here also.

They can be pretty pricey, particularly if you are limited to one model only. It's a bit of a confusing issue as Yamaha manuals are known to contain errors, so choosing based on published timing advance data just doesn't yield a reliable result.

 

The below pic is a XJ550 , does the XJ650 match?